Many gas turbine engines use a heat exchanger of recuperator to increase the operation efficiency of the engine by extracting heat from the exhaust gas and preheating the intake air. Typically, a recuperator for a gas turbine engine must be capable of operating at temperatures of between about 500 degrees C. and 700 degrees C. and internal pressures of between approximately 450 kPa and 1400 kPa under operating conditions involving repeated starting and stopping cycles.
Such circular recuperators include a core which is commonly constructed of a plurality of relatively thin flat sheets having an angled or corrugated spacer fixedly attached therebetween. The sheets are joined into cells and sealed at opposite sides and form passages between the sheets. These cells are stacked or rolled and form alternative air cells and hot exhaust cells. Compressed discharged air from a compressor of the engine passes through the air cell while hot exhaust gas flows through alternate cells. The exhaust gas heats the sheets and the spaces, and the compressor discharged air is heated by conduction from the sheets and spacers.
An example of such a recuperator is disclosed in U.S. Pat. No. 5,060,721 issued to Charles T. Darragh on Oct. 29, 1991. In such a system, a heat exchanger having been used to increase the efficiency of engine by absorbing heat from the exhaust gases and transferring a portion of the exhaust heat to the intake air is disclosed. The heat exchanger is built-up from a plurality of performed involute curved cells stacked in a circular array to provide flow passages and for the donor fluid and the recipient fluid respectively.
The construction of such cells when having each of the components formed prior to assembly increases cost, time and complexity of the assembly process. Additionally, the variation of tolerance between individual sheets or components increases assembly cost, time and complexity.
The present invention is directed to overcoming one or more of the problems as set forth above.